Effect of Flowing Rate on Galvanic Corrosion Associated with 316L/2205 and 431/2205 Stainless Steel Couples in 3.5% NaCl Solution

Effect of flowing on galvanic corrosion of 316L/2205 and 431/2205 couples in 3.5% NaCl solution was investigated by potentiodynamic polarization,galvanic current and corrosion morphology analyses.The galvanic behavior of these couples was compared with that of 42CrMo/316L couple.The results showed that 316L,431 and 42CrMo were anode,respectively.The galvanic corrosion tendency of these couples was shown as follows: 316L/2205< 431/2205< 42CrMo/316L.The galvanic current measurement revealed that flowing increased the galvanic current.Oscillation peaks in both galvanic potential and current curves were observed under flowing condition for the 431/2205 couple.Corrosion morphology analyses indicated that there were no obvious corrosion on 316L,431 and 2205 stainless steels in the static solution and a rust layer formed on the surface of 42CrMo steel.Under flowing condition,pits covered with rust on 431 stainless steel were observed,surface of 42CrMo steel was covered with corrosion products.It is considered that the oscillation peaks of current density for 431/2205 couples is possibly attributed to the formation of rust on the pits under flowing condition.